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Utilisation of Synthetic Gypsum from FGDs

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This article discusses the quality and quantities of limestone requirements for Flue Gas Desulfurisation (FGD) with expected quality of synthetic gypsum (SG) generated from power plants. As this development is a win-win situation for power and cement, various possibilities of collaboration between these two major industries are discussed in this article.

The Ministry of Environment & Forests (MOEF) vide their notification dated December 7, 2015 has prescribed limits for particulate and gaseous emissions from all the thermal power plants in India. As per the notifications, the SOx emissions are to be brought down to level of <600 mg/NM3 for plants (installed before 2016) and all the plants have to complied with this limit within 2 years from the date of notification. As on date, the coal-based thermal power generation capacity in India is about 1.96 lakh MW and it is projected by the Ministry Of Power (MOP), following implementation schedule of FGDs by thermal power plants.

A few of the thermal power plants have already initiated projects for meeting the above schedules and over a period of next seven years, all the FGD projects of thermal power plants will come on stream, producing synthetic gypsum. Majority of the power plants are considering wet process FGD technology, using limestone slurry.

FGD in power plants
Globally, Flue Gas Desulfurisation (FGD) systems have been installed in many thermal power plants in developed countries and FGD plants have been in operation in US since 40 years. Proven technologies are available for FGD in power plants. The technologies are primarily based on limestone and lime products such as quick lime or hydrated lime. FGD plants-based wet process technology, which uses limestone slurry is the most prevalent technologies in the US and China. In this process, the gaseous SOx is absorbed in limestone slurry and forms synthetic gypsum (SG).

SG as a substitute for mineral gypsum by cement industry is well established in the US and the following pattern of usage of SG reflects the usage in cement. The entire demand of gypsum of cement industry in the US is met by SG generated in FGDs of power plants in the country.

It can be expected, SG from FGDs of thermal power plants can become a major source of gypsum for the Indian cement industry. It can become a substitute for imported gypsum consumption by industry and also make up shortfalls in supply of mineral gypsum by indigenous gypsum mines.

Limestone requirements for FGDs
The quality requirements of Limestone suitable for FGDs are defined in FGD specification documents of the Central Electricity Authority (CEA). It is to be noted that the quality requirements are similar to the limestone quality requirement for clinker production. Higher the lime content in limestone, the purity of SG produced by FGDs will be better.

Typically, the limestone requirement for FGD plant with sulfur content of 0.5-0.7 per cent in coal fired in power plants is about 0.23-0.30 TPD of limestone/MW installed capacity. It is estimated that limestone demand by FGD systems will be about 15 million tonnes per annum (MTPA) by 2022.

Synthetic gypsum (SG)
FGD plants of wet process technology generate a solid product, which has similar chemical composition of gypsum i.e. CaSO4.2H20. This product, in the form of Slurry is collected at the bottom of the SOx absorption tower. The slurry passes through belt filters to generate filter cake of about 10-12 per cent moisture. This cake is stored in open spaces for sun drying and also for loading into trucks/wagons.

The expected quality of per cent from wet FGDs is as follows:
Gypsum Purity (as CaSO4.2H20, dry) – > 80-90 per cent (depends on LS quality)
Free moisture: 10-12 per cent
Particle size : 100 per cent passing 200 microns
Though above parameters are similar to Phospho gypsum, SG is not having phosphoric compounds and hence the setting times achieved with usage of SG is as good as that for mineral gypsum.

Gypsum Availability for Cement Industry
At present, in India, out of about 13.5 MT of gypsum (all types) consumed, 99 per cent of gypsum is used by cement industry. Due to shortage of gypsum production in India, about 4.0 million tons of mineral gypsum is imported over last few years from countries like Oman, Pakisthan and the UAE.

Gypsum consumption pattern
It is noted that consumption in cement industry is about 99 per cent of total gypsum consumption in India. During the year 2015-16, apart from mineral, marine and by-product gypsum sourced from India, about 4.6 MT of mineral gypsum was imported from Oman, UAE, Pakistan and Thailand. The purity of imported gypsum is about 85 per cent whereas mineral gypsum from Rajasthan have a quality of 60-75 per cent. The purity of imported gypsum is about 85 per cent whereas mineral gypsum from Rajasthan have a quality of 65-75 per cent. Because of low purity of Mineral Gypsum produced by Mines in India, a majority of the consumers are either moving to imported gypsum or a blend of mineral gypsum with high purity Phospho or chemical gypsum.

SG – Expected capacity and quality
The Product of FGD is Gypsum and as it is not a natural gypsum, it is called SG. SG of FGD is going to be available in large quantities in India in future as all Power plants have to installs FGDs for Control of SO2, With present power generation capacity of coal based power plants in India, it is estimated that the SG generation by Power sector is going to approximately 23 MT per year. This SG capacity can entirely meet the gypsum demand of the country in future, considering the growth projections of cement and wall board industries. At present these two industries, consume about 99 per cent of all types of gypsum consumption in India.

Expected quality of SG
The purity of SG generated by FGD is expected to be 82-88 per cent depending the purity of Limestone used. SG will have a moisture of < 12 per cent with fineness of 100 per cent passing 200 microns and the temperature at absorption tower outlet is about 50 deg C. The expected quality of SG by FGD as compared to other types of Gypsum given below. It can be seen that the expected quality of SG from FGD plants is as good as by product gypsum and unlike Phospho-gypsum, SG will not have the problem of delayed setting, due to absence phosphoric oxides.

In the US, apart from cement industries, wallboard industry is a major customer for SG utilisation. Though this industry is in nascent stages in India, boards made out of gypsum are becoming more and more popular in India for partition walls in high rise building, which results in substantial reduction of construction costs and time. All the major multinationals like Saint Gobain (Gyproc), Boral & Gyp Elite, India have already started manufacturing gypsum boards in India and have plans for expansion of existing plants and also to establish new manufacturing facilities.

In the next two years, the total wall/plaster board industry is expected reach a capacity of >1.5 MTPA and the demand for gypsum is expected to be > 1.2 MTPA. Various data from developed nations indicate that, the quality of SG from FGD plants can replace completely the traditional source of gypsum i.e. Mineral gypsum, thus conserving the natural gypsum in the country and reduced mining activities of gypsum. In India, by year 2022, with the projected availability of SG> 15 MTPA, it can completely eliminate the imports of gypsum, meeting the projected demands of cement and wallboard industry.

Recommendation for processing of SG
One of the major impediments for selling SG to cement and wall board industry is the high moisture content of SG (10-12 per cent), when it is generated at FGD plant. The cement industry (especially grinding units within a distance of 300 km) and paperboard industry traditionally use mineral gypsum, which contains a moisture content of <3 per cent. Hence handling, storage and processing of mineral gypsum is easy as compared to SG at these locations. This is one of the reasons for giving first priotiry for Mineral Gypsum by cement plants. Because of higher moisture content in SG, the logistics costs are higher for SGsts and also additional costs for drying by customers.

Action plan
It is expected that, over next five years, the availability of SG from power plants can become a major source of gypsum for cement industry. It is necessary for cement industry to initiate actions, the merits and demerits for its usage are elaborated below.

Merits: As the purity of SG is better than indigenous mineral gypsum and also it is in powder form, the usage factors such % consumption and specific energy consumption are favourable for it usage. SG is expected to have a more consistent quality as compared to Mineral gypsum. SG can partially or fully replace usage of Phospho-gypsum. As SG is a disposal problem for power plants, the landed costs of SG at cement plants will be attractive.

Demerits: As SG contains a moisture of 10-12 per cent, unloading and handling, storage and dosing systems of existing plants may require a revamp.

Suggested initiatives for SG utilisation
As utilisation by SG by cement industry is a win-win situation for both power and cement sectors, following initiatives may be considered:
Utilisation of SG for cement production is a new concept for Indian Cement Industry. Hence, as a first step, cement producers to carryout laboratory testing of SG from FGD plants, which are in operation and access its technical feasibility for its usage.
Once it is technical is feasible, Cement companies should carry out plant trials for arriving at the optimum levels of SG utilisation in their plants.
The Plant specific quality requirements of SG can be intimated to the Identified power plants from where SG can be supplied.
Short and long term contracts can be worked out between Cement & Power plants for supply of SG.

Common initiative
As limestone is required for FGDs, Integrated cement units can have an understanding with power producers about supply of Limestone to FGDs and in return and receive SG from Power producers. This will benefit both the sectors as it optimises the landed costs at both ends.

This initiative may require revision of conditions of ML for Limestone by cement companies and hence, a joint initiative to be taken up by CMA and CEA for representation with concerned departments of State/Central governments for relaxation of ML conditions and also for incentives for cement industry for reducing the problem of disposal of SG. Cement and power producers can also jointly explore the possibility of installing SG dryers at Power plants to reduce the handling, transport and dosing problems associated with wet SG.

Conclusion
For next five years, problem of disposal of SG generated from FGDs of power plants is going to be a major issue for power plants. It is an opportunity for cement industry for utilisation of SG in cement production and usage of SG in cement, not only reduces/eliminates the disposal problem but also substitute the mineral gypsum (imported/indigenous), used by the industry. Considering an availability of 15 MTPA of SG in the next five years, it can sustain a cement production capacity of about 350 MTPA. SG can act as import substitute and also conserve the scare resources of mineral gypsum in the country.

About the author:
Satyamurthy V. Yenamandra (Y. V. Satyamurthy)
is a consultant for cement and mineral industries with over 35 years working experience in ACC and Reliance Cement in functional areas of process and project engineering, project management and training.

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Economy & Market

Impactful Branding

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Advertising or branding is never about driving sales. It’s about creating brand awareness and recall. It’s about conveying the core values of your brand to your consumers. In this context, why is branding important for cement companies? As far as the customers are concerned cement is simply cement. It is precisely for this reason that branding, marketing and advertising of cement becomes crucial. Since the customer is unable to differentiate between the shades of grey, the onus of creating this awareness is carried by the brands. That explains the heavy marketing budgets, celebrity-centric commercials, emotion-invoking taglines and campaigns enunciating the many benefits of their offerings.
Marketing strategies of cement companies have undergone gradual transformation owing to the change in consumer behaviour. While TV commercials are high on humour and emotions to establish a fast connect with the customer, social media campaigns are focussed more on capturing the consumer’s attention in an over-crowded virtual world. Branding for cement companies has become a holistic growth strategy with quantifiable results. This has made brands opt for a mix package of traditional and new-age tools, such as social media. However, the hero of every marketing communication is the message, which encapsulates the unique selling points of the product. That after all is crux of the matter here.
While cement companies are effectively using marketing tools to reach out to the consumers, they need to strengthen the four Cs of the branding process – Consumer, Cost, Communication and Convenience. Putting up the right message, at the right time and at the right place for the right kind of customer demographic is of utmost importance in the long run. It is precisely for this reason that regional players are likely to have an upper hand as they rely on local language and cultural references to drive home the point. But modern marketing and branding domain is exponentially growing and it would be an interesting exercise to tabulate and analyse its impact on branding for cement.

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Concrete

Indian cement industry is well known for its energy and natural resource efficiency

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Dr Hitesh Sukhwal, Deputy General Manager – Environment, Udaipur Cement Works Limited (UCWL) takes us through the multifaceted efforts that the company has undertaken to keep emissions in check with the use of alternative sources of energy and carbon capture technology.

Tell us about the policies of your organisation for the betterment of the environment.
Caring for people is one of the core values of our JK Lakshmi Cement Limited. We strongly believe that we all together can make a difference. In all our units, we have taken measures to reduce carbon footprint, emissions and minimise the use of natural resources. Climate change and sustainable development are major global concerns. As a responsible corporate, we are committed with and doing consistent effort small or big to preserve and enrich the environment in and around our area of operations.
As far as environmental policies are concerned, we are committed to comply with all applicable laws, standards and regulations of regulatory bodies pertaining to the environment. We are consistently making efforts to integrate the environmental concerns into the mainstream of the operations. We are giving thrust upon natural resource conservation like limestone, gypsum, water and energy. We are utilising different kinds of alternative fuels and raw materials. Awareness among the employees and local people on environmental concerns is an integral part of our company. We are adopting best environmental practices aligned with sustainable development goals.
Udaipur Cement Works Limited is a subsidiary of the JK Lakshmi Cement Limited. Since its inception, the company is committed towards boosting sustainability through adopting the latest art of technology designs, resource efficient equipment and various in-house innovations. We are giving thrust upon renewable and clean energy sources for our cement manufacturing. Solar Power and Waste Heat Recovery based power are our key ingredients for total power mix.

What impact does cement production have on the environment? Elaborate the major areas affected.
The major environmental concern areas during cement production are air emissions through point and nonpoint sources due to plant operation and emissions from mining operation, from material transport, carbon emissions through process, transit, noise pollution, vibration during mining, natural resource depletion, loss of biodiversity and change in landscape.
India is the second largest cement producer in the world. The Indian cement industry is well known for its energy and natural resource efficiency worldwide. The Indian cement industry is a frontrunner for implementing significant technology measures to ensure a greener future.
The cement industry is an energy intensive and significant contributor to climate change. Cement production contributes greenhouse gases directly and indirectly into the atmosphere through calcination and use of fossil fuels in an energy form. The industry believes in a circular economy by utilising alternative fuels for making cement. Cement companies are focusing on major areas of energy efficiency by adoption of technology measures, clinker substitution by alternative raw material for cement making, alternative fuels and green and clean energy resources. These all efforts are being done towards environment protection and sustainable future.
Nowadays, almost all cement units have a dry manufacturing process for cement production, only a few exceptions where wet manufacturing processes are in operation. In the dry manufacturing process, water is used only for the purpose of machinery cooling, which is recirculated in a closed loop, thus, no polluted water is generated during the dry manufacturing process.
We should also accept the fact that modern life is impossible without cement. However, through state-of-the-art technology and innovations, it is possible to mitigate all kinds of pollution without harm to the environment and human beings.

Tell us about the impact blended cement creates on the environment and emission rate.
Our country started cement production in 1914. However, it was introduced in the year 1904 at a small scale, earlier. Initially, the manufacturing of cement was only for Ordinary Portland Cement (OPC). In the 1980s, the production of blended cement was introduced by replacing fly ash and blast furnace slag. The production of blended cement increased in the growth period and crossed the 50 per cent in the year 2004.
The manufacturing of blended cement results in substantial savings in the thermal and electrical energy consumption as well as saving of natural resources. The overall consumption of raw materials, fossil fuel such as coal, efficient burning and state-of-the-art technology in cement plants have resulted in the gradual reduction of emission of carbon dioxide (CO2). Later, the production of blended cement was increased in manifolds.
If we think about the growth of blended cement in the past few decades, we can understand how much quantity of , (fly ash and slag) consumed and saved natural resources like limestone and fossil fuel, which were anyhow disposed of and harmed the environment. This is the reason it is called green cement. Reduction in the clinker to cement ratio has the second highest emission reduction potential i.e., 37 per cent. The low carbon roadmap for cement industries can be achieved from blended cement. Portland Pozzolana Cement (PPC), Portland Slag Cement (PSC) and Composite Cement are already approved by the National Agency BIS.
As far as kilogram CO2 per ton of cement emission concerns, Portland Slag Cement (PSC) has a larger potential, other than PPC, Composite Cement etc. for carbon emission reduction. BIS approved 60 per cent slag and 35 per cent clinker in composition of PSC. Thus, clinker per centage is quite less in PSC composition compared to other blended cement. The manufacturing of blended cement directly reduces thermal and process emissions, which contribute high in overall emissions from the cement industry, and this cannot be addressed through adoption of energy efficiency measures.
In the coming times, the cement industry must relook for other blended cement options to achieve a low carbon emissions road map. In near future, availability of fly ash and slag in terms of quality and quantity will be reduced due to various government schemes for low carbon initiatives viz. enhance renewable energy sources, waste to energy plants etc.
Further, it is required to increase awareness among consumers, like individual home builders or large infrastructure projects, to adopt greener alternatives viz. PPC and PSC for more sustainable
resource utilisation.

What are the decarbonising efforts taken by your organisation?
India is the world’s second largest cement producer. Rapid growth of big infrastructure, low-cost housing (Pradhan Mantri Awas Yojna), smart cities project and urbanisation will create cement demand in future. Being an energy intensive industry, we are also focusing upon alternative and renewable energy sources for long-term sustainable business growth for cement production.
Presently, our focus is to improve efficiency of zero carbon electricity generation technology such as waste heat recovery power through process optimisation and by adopting technological innovations in WHR power systems. We are also increasing our capacity for WHR based power and solar power in the near future. Right now, we are sourcing about 50 per cent of our power requirement from clean and renewable energy sources i.e., zero carbon electricity generation technology. Usage of alternative fuel during co-processing in the cement manufacturing process is a viable and sustainable option. In our unit, we are utilising alternative raw material and fuel for reducing carbon emissions. We are also looking forward to green logistics for our product transport in nearby areas.
By reducing clinker – cement ratio, increasing production of PPC and PSC cement, utilisation of alternative raw materials like synthetic gypsum/chemical gypsum, Jarosite generated from other process industries, we can reduce carbon emissions from cement manufacturing process. Further, we are looking forward to generating onsite fossil free electricity generation facilities by increasing the capacity of WHR based power and ground mounted solar energy plants.
We can say energy is the prime requirement of the cement industry and renewable energy is one of the major sources, which provides an opportunity to make a clean, safe and infinite source of power which is affordable for the cement industry.

What are the current programmes run by your organisation for re-building the environment and reducing pollution?
We are working in different ways for environmental aspects. As I said, we strongly believe that we all together can make a difference. We focus on every environmental aspect directly / indirectly related to our operation and surroundings.
If we talk about air pollution in operation, every section of the operational unit is well equipped with state-of-the-art technology-based air pollution control equipment (BagHouse and ESP) to mitigate the dust pollution beyond the compliance standard. We use high class standard PTFE glass fibre filter bags in our bag houses. UCWL has installed the DeNOx system (SNCR) for abatement of NOx pollution within norms. The company has installed a 6 MW capacity Waste Heat Recovery based power plant that utilises waste heat of kiln i.e., green and clean energy source. Also, installed a 14.6 MW capacity solar power system in the form of a renewable energy source.
All material transfer points are equipped with a dust extraction system. Material is stored under a covered shed to avoid secondary fugitive dust emission sources. Finished product is stored in silos. Water spraying system are mounted with material handling point. Road vacuum sweeping machine deployed for housekeeping of paved area.
In mining, have deployed wet drill machine for drilling bore holes. Controlled blasting is carried out with optimum charge using Air Decking Technique with wooden spacers and non-electric detonator (NONEL) for control of noise, fly rock, vibration, and dust emission. No secondary blasting is being done. The boulders are broken by hydraulic rock breaker. Moreover, instead of road transport, we installed Overland Belt Conveying system for crushed limestone transport from mine lease area to cement plant. Thus omit an insignificant amount of greenhouse gas emissions due to material transport, which is otherwise emitted from combustion of fossil fuel in the transport system. All point emission sources (stacks) are well equipped with online continuous emission monitoring system (OCEMS) for measuring parameters like PM, SO2 and NOx for 24×7. OCEMS data are interfaced with SPCB and CPCB servers.
The company has done considerable work upon water conservation and certified at 2.76 times water positive. We installed a digital water flow metre for each abstraction point and digital ground water level recorder for measuring ground water level 24×7. All digital metres and level recorders are monitored by an in-house designed IoT based dashboard. Through this live dashboard, we can assess the impact of rainwater harvesting (RWH) and ground water monitoring.
All points of domestic sewage are well connected with Sewage Treatment Plant (STP) and treated water is being utilised in industrial cooling purposes, green belt development and in dust suppression. Effluent Treatment Plant (ETP) installed for mine’s workshop. Treated water is reused in washing activity. The unit maintains Zero Liquid Discharge (ZLD).
Our unit has done extensive plantations of native and pollution tolerant species in industrial premises and mine lease areas. Moreover, we are not confined to our industrial boundary for plantation. We organised seedling distribution camps in our surrounding areas. We involve our stakeholders, too, for our plantation drive. UCWL has also extended its services under Corporate Social Responsibility for betterment of the environment in its surrounding. We conduct awareness programs for employees and stakeholders. We have banned Single Use Plastic (SUP) in our premises. In our industrial township, we have implemented a solid waste management system for our all households, guest house and bachelor hostel. A complete process of segregated waste (dry and wet) door to door collection systems is well established.

Tell us about the efforts taken by your organisation to better the environment in and around the manufacturing unit.
UCWL has invested capital in various environmental management and protection projects like installed DeNOx (SNCR) system, strengthening green belt development in and out of industrial premises, installed high class pollution control equipment, ground-mounted solar power plant etc.
The company has taken up various energy conservation projects like, installed VFD to reduce power consumption, improve efficiency of WHR power generation by installing additional economiser tubes and AI-based process optimisation systems. Further, we are going to increase WHR power generation capacity under our upcoming expansion project. UCWL promotes rainwater harvesting for augmentation of the ground water resource. Various scientifically based WHR structures are installed in plant premises and mine lease areas. About 80 per cent of present water requirement is being fulfilled by harvested rainwater sourced from Mine’s Pit. We are also looking forward towards green transport (CNG/LNG based), which will drastically reduce carbon footprint.
We are proud to say that JK Lakshmi Cement Limited has a strong leadership and vision for developing an eco-conscious and sustainable role model of our cement business. The company was a pioneer among cement industries of India, which had installed the DeNOx (SNCR) system in its cement plant.

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Concrete

NTPC selects Carbon Clean and Green Power for carbon capture facility

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Carbon Clean and Green Power International Pvt. Ltd has been chosen by NTPC Energy Technology Research Alliance (NETRA) to establish the carbon capture facility at NTPC Vindhyachal. This facility, which will use a modified tertiary amine to absorb CO2 from the power plant’s flue gas, is intended to capture 20 tonnes of CO2) per day. A catalytic hydrogenation method will eventually be used to mix the CO2 with hydrogen to create 10 tonnes of methanol each day. For NTPC, capturing CO2 from coal-fired power plant flue gas and turning it into methanol is a key area that has the potential to open up new business prospects and revenue streams.

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